Function copy

src/include/buffer.h:708–711

      void copy(unsigned len, std::string &dest);
      template<typename A>
      void copy(unsigned len, std::vector<uint8_t,A>& u8v) {
        u8v.resize(len);
        copy(len, (char*)u8v.data());
      }

      void copy_all(list &dest);